Cummins (1980; 1981; 1996) theorized that there are two kinds of English proficiency that ESL students must learn. The first Basic Interpersonal Conversational Skills (BICS) involves the ability to converse with others and to articulate needs in L2, and can be developed only 2-3 years. The other is Cognitive Academic Language Proficiency (CALP). CALP involves the acquisition of academic literacy skills, and the use of L2 to understand complex, decontextualized linguistic structures, and to analyze, explore, and deconstruct the concepts presented in academic texts. It takes between 5-7 years to master CALP. Cummins argues that ESL learners cannot acquire cognitive academic language skills from everyday conversation. Developing these cognitive skills requires task-based, experiential learning typified by learners’ interactions with contexts, tasks, and texts that present them with complex interdisciplinary context. Thus, Cummin’s model provides another theoretical foundation for CBI.
In the fictional conversation vignette, Jeffery has high BICS English level; however, he needs strong CALP English to assist him to be academically successful in school performance.